Co-authored-by: sgomes <sergiomdgomes@git.wordpress.org>
Co-authored-by: swissspidy <swissspidy@git.wordpress.org>
Co-authored-by: andrewserong <andrewserong@git.wordpress.org>

Co-authored-by: sgomes <sergiomdgomes@git.wordpress.org>
Co-authored-by: swissspidy <swissspidy@git.wordpress.org>
Co-authored-by: andrewserong <andrewserong@git.wordpress.org>

Fix unintended revert of #76780 during rebase. The promise-based
approach ensures only a single Vips instance is ever created, even
when multiple callers race on initialization.

Co-authored-by: sgomes <sergiomdgomes@git.wordpress.org>
Co-authored-by: swissspidy <swissspidy@git.wordpress.org>
Co-authored-by: andrewserong <andrewserong@git.wordpress.org>

* Use image.copyMemory() for batch thumbnail generation

Decode the source image once via copyMemory() and use thumbnailImage()
for each sub-size, instead of re-decoding the source buffer for every
thumbnail. This approach was suggested by the wasm-vips maintainer
and avoids both re-decoding overhead and the need for intermediate
format conversions.

The new batchResizeImage() function in the vips package materializes
the decoded image in WASM memory, then generates all thumbnails from
that single in-memory copy. Results are written directly to the target
output format, eliminating separate transcode steps.

Falls back to per-thumbnail processing if the batch operation fails.

* Restore vipsPromise singleton pattern in getVips()

Fix unintended revert of #76780 during rebase. The promise-based
approach ensures only a single Vips instance is ever created, even
when multiple callers race on initialization.

* Extract shared resize/crop logic into common helpers

Add applyResizeAndCrop() to consolidate the duplicated dimension
calculation and crop logic between resizeImage and batchResizeImage.
Add buildSaveOptions() to unify save option construction, which also
fixes the missing AVIF effort=2 setting in resizeImage.

* Address review nits in applyResizeAndCrop and batchResizeImage

Clone the resize config into a local target object rather than mutating
the caller's ImageSizeCrop parameter, and drop an unused strOptions
constant in batchResizeImage.

The feature shipping target moved from 7.0 to 7.1 (per #76756). Bring
the architecture explanation and how-to guide up to date with the
post-7.0-cycle state of the code:

- Reposition introductions around 7.1 with 7.0 as the groundwork cycle.
- HEIC/HEIF: document the canvas-based fallback path (createImageBitmap,
  HTMLImageElement+OffscreenCanvas, HEIC container parsing + WebCodecs
  VideoDecoder), JPEG companion file, and isHeicCanvasSupported() gate.
- AVIF: note the wp_prevent_unsupported_mime_type_uploads bypass when
  generate_sub_sizes=false (#76371).
- Batch thumbnail generation via image.copyMemory() / thumbnailImage()
  (#76979).
- Sub-size deduplication via image_size: string|string[] on the sideload
  route (#77036).
- Single VIPS instance via promise caching (#76780).
- Build-output trimming: remove vips-jxl.wasm (#76639), skip non-min
  worker (#76615), skip WASM-inlined sourcemaps (#75993).
- COI: <img> excluded from cross-origin attribute injection (#76618).
- Loosened feature-detection thresholds: 2 cores, 3g (#76616).
- Post-saving lock fix: Save Draft now respects the lock (#76973).
- convert_format declared as boolean on sideload route (#77565).
- Fix incorrect REST index settings list (only image_sizes and
  image_size_threshold are exposed).
- Remove references to client_side_supported_mime_types filter
  (PR #76549 was closed unmerged); state the supported MIME set is
  fixed at CLIENT_SIDE_SUPPORTED_MIME_TYPES.

Refs #75111.